基于波速测量的龙马溪组页岩的各向异性研究  

Study on Longmaxi Formation Shale Anisotropy Based on Acoustic Wave Velocity Measurement

作　　者：袁和义 陈平[1] Yuan Heyi Chen Pingt(State Key Lab of Oil ＆ Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chendu 610500, P.R. China Petro China Southwest Oil ＆ Gas Field Company, Sichuan Northwest Gas, Jiangyou, Sichuan, 621709, P.R. China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,成都610500 [2]中国石油西南油气田公司川西北气矿,四川江油621709

出　　处：《地下空间与工程学报》2017年第5期1200-1205,共6页Chinese Journal of Underground Space and Engineering

基　　金：国家重点基础研究发展计划课题(2013CB228003)

摘　　要：随页岩气开采大力发展,对页岩的认识也逐显重要。页岩作为明显的层状结构岩石,普遍表现出各向异性。为此,基于横观各向同性介质模型,通过测量岩样不同方向的纵波波速和快慢横波波速,计算了长宁区块龙马溪组岩样的刚度系数与弹性系数,并与静载荷试验测定的弹性参数做出对比。试验结果表明,页岩的纵波波速以及快慢横波波速均表现出各向异性,并且随围压升高,波速升高速率变缓。岩样的杨氏模量与泊松比亦表现出各向异性,水平方向上的杨氏模量始终高于垂直方向上的杨氏模量,而3个方向的泊松比不一致。动态加载测试值与静态加载测试值随围压变化趋势一致,并且随围压升高,由孔隙和微裂缝引起各向异性减弱。考虑页岩中微裂缝的存在,通过弥散损伤模型计算龙马溪组页岩的损伤参数,认为在围压作用下微裂缝主要存在于平行层理面方向,围压对垂直层理面的裂缝影响较小。With shale gas development vigorously,the understanding of shale is also important. Shale generally shows anisotropy. Based on VTI model,the vP,vSV,vSHin different directions were measured,and the stiffness coefficient and elastic coefficient of rock sample were calculated. The results show that： vP,vSVand vSHshow anisotropy in different directions,and the acoustic wave velocity increase with confining pressure. Young＇s modulus and Poisson＇s ratio also behave anisotropy,the Young＇s modulus in isotropic plane always exceed the Young＇s modulus parallel to the axis of symmetry,and the Poisson＇s ratio is variant in different directions. Elastic anisotropy is due to the combined effects of pores or cracks and mineral grain orientation,and elastic anisotropy decreases with increasing confining pressure. The residual anisotropy at higher confining pressure is due to mineral grain orientation.The damage parameters by diffuse damage modeling were calculated when considering the crack-void,and at atmospheric pressure,there are more horizontally oriented crack-like voids than vertically oriented.

关 键 词：龙马溪页岩 各向异性 声波波速 弹性参数 弥散性损伤 

分 类 号：TE12[石油与天然气工程—油气勘探]